Scientific AmericanSupplement July 11 1891

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July 11, 1891, by Various

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Title: Scientific American Supplement, No. 810, July 11, 1891

Author: Various

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Language: English

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SCIENTIFIC AMERICAN SUPPLEMENT

NO. 810

NEW YORK, July 11, 1891

Scientific American Supplement. Vol. XXXII, No. 810.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

TABLE OF CONTENTS.

I.
BOTANY.—Cocos Pynaerti.—A new dwarf growing palm.—1 illustration.

II.
CHEMISTRY.—The Application of Electrolysis to Quantitative Analysis.—By CHARLES A.
KOHN, B.Sc., Ph.D.—Applicability of these methods to poison determinations.

III.
CIVIL ENGINEERING.—The Kioto-Fu Canal in Japan.—A Japanese canal connecting the
interior of the country with the sea.—3 illustrations.
The Iron Gates of the Danube.—An important engineering work, opening a channel in the Danube.
—1 illustration.
The New German Ship Canal.—Connection of the Baltic with the North Sea.—Completion of this
work.—1 illustration.

Transit in London, Rapid and Otherwise.—By JAMES A. TILDEN.—A practical review of
London underground railroads and their defects and peculiarities.

IV.
ELECTRICITY.—An Electrostatic Safety Device.—Apparatus for grounding a circuit of too high
potential.—1 illustration.
Experiments with High Tension Alternating Currents.—Sparking distance of arc formed by a
potential difference of 20,000 volts.—1 illustration.
Laying a Military Field Telegraph Line,—Recent field trials in laying telegraph line in England.—3
illustrations.
Some Experiments on the Electric Discharge in Vacuum Tubes.—By Prof. J.J. THOMSON, M.A.,
F.R.S.—Interesting experiments described and illustrated.—4 illustrations.
The Electrical Manufacture of Phosphorus.—Note upon a new English works for this industry.

V.
GEOGRAPHY.—The Mississippi River.—By JACQUES W. REDWAY.—An interesting paper
on the great river and its work and history.

VI.
MECHANICAL ENGINEERING.—How to Find the Crack.—Note on a point in foundry work.
Riveted Joints in Boiler Shells.—By WILLIAM BARNET LE VAN.—Continuation of this practical
and important paper.—10 illustrations.

VII. MEDICINE AND HYGIENE.—Influence of Repose on the Retina.—Important researches on the

physiology of the eye.
The Relation of Bacteria to Practical Surgery.—By JOHN B. ROBERTS, A.M., M.D.—A full
review from the surgeon's standpoint of this subject, with valuable directions for practitioners.

VIII. MINERALOGY.—Precious and Ornamental Stones and Diamond Cutting.—By GEORGE

FREDERICK KUNZ.—An abstract from a recent census bulletin, giving interesting data.

IX.
MINING ENGINEERING.—Mine Timbering.—The square system of mine timbering as used in
this country in the Pacific coast mines and now introduced into Australia.—1 illustration.

X.
MISCELLANEOUS.—Freezing Mixtures.—A list of useful freezing mixtures.
Sun Dials.—Two interesting forms of sun dials described.—3 illustrations.
The Undying Germ Plasm and the Immortal Soul.—By DR. R. VON LENDENFELD.—A curious
example of modern speculative thought.

XI.
NAVAL ENGINEERING.-The New British Battle Ship Empress of India.—A first class battle ship
recently launched at Pembroke dockyard.

XII. TECHNOLOGY.—Composition of Wheat Grain and its Products in the Mill.—A scientific

examination of the composition of wheat and its effect on mill products.
Fast and Fugitive Dyes.—By Prof. J.J. HAMMEL.—Practical notes from the dyer's standpoint
upon coloring agents.

MINE TIMBERING.

The square system of timbering, in use in most of our large mines on the Pacific coast, was first introduced in
Australia by Mr. W.H. Patton, who adopted it in the Broken Hill Proprietary mines, although it does not
seem to be so satisfactory to the people there as to our miners, who are more familiar with it. The
accompanying description and plans were furnished by Mr. Patton to the report of the Secretary of Mines
for Victoria:

"The idea is supposed to have originated in the German mines, but in a crude form. It was
introduced among the mines of the Pacific coast of America some 20 years ago, by a gentleman
named Diedesheimer. Its use there is universal, and experience has evolved it from the embryo
state to its present perfection. The old system and its accompanying disadvantages are well
known. A drive would be put in for a certain distance, when it had to be abandoned until it
could be filled up with waste material and made secure. This process entailed much expense.
The stuff had first to be broken on the surface, then sent below, trucked along the drives, and
finally shoveled into place. Ventilation was impaired and the drives were filled with dust. The
men worked in discomfort, and were not in a condition to perform a full measure of labor.
Under the system as adopted in the Proprietary mine, these disadvantages disappear. The cost
is one-third less, ventilation is perfect, and every portion of the faces are accessible at all times.
Sawn timber is used throughout; the upright and cross pieces are 10 inches by 10 inches, and
stand 4 feet 6 inches apart; along the course of the drive, the cross pieces are five feet in length,
and the height of the main drives and sill floor sets are 7 feet 2 inches in the clear. In blocking
out the stopes, the uprights are 6 feet 2 inches, just one foot shorter than those in the main
drives. The caps and struts are of the same dimensions and timber as the sill floor. The planks
used as staging are 9 inches by 2½ inches; they are moved from place to place as required, and

upon them the men stand when working in the stopes and in the faces. A stope resembles a
huge chamber fitted with scaffolding from floor to roof. The atmosphere is cool and pure, and
there is no dust. Stage is added to stage, according as the stoping requires it, and ladders lead
from one floor to the other; the accessibility to all the faces is a great advantage.

If, while driving, a patch of low grade ore is met with, it can be enriched by taking a higher class
from another face, and so on. Any grade can be produced by means of this power of selection.
Opinions have been expressed that this system of timbering is not secure, and that pressure
from above would bring the whole structure down in ruins. But an opinion such as this is due to
miscomprehension of the facts. If signs of weakening in the timbers become apparent, the
remedy is very simple. Four or more of the uprights are lined with planks, and waste material is
shot in from above, and a strong support is at once formed, or if signs of crushing are noticed, it
is possible to go into the stope, break down ore, and at once relieve the weight."

THE SQUARE SYSTEM OF TIMBERING IN MINES.

TRANSIT IN LONDON, RAPID AND OTHERWISE.1

By JAMES A. TILDEN.

The methods of handling the travel and traffic in the city of London form a very interesting subject for the
study of the engineer. The problem of rapid transit and transportation for a city of five millions of inhabitants
is naturally very complicated, and a very difficult one to solve satisfactorily.

The subject may be discussed under two divisions: first, how the suburban travel is accommodated, that is,
the great mass of people who come into the business section of the city every morning and leave at night;
second, how the strictly local traffic from one point to another is provided for. Under the first division it will
be noted in advance that London is well provided with suburban railroad accommodation upon through lines
radiating in every direction from the center of the city, but the terminal stations of these roads, as a rule, do
not penetrate far enough into the heart of the city to provide for the suburban travel without some additional
methods of conveyance.

The underground railroad system is intended to relieve the traffic upon the main thoroughfares, affording a
rapid method of transportation between the residential and business portions, and in addition to form a
communicating link between the terminals of the roads referred to. These terminal stations are arranged in the
form of an irregular ellipse and are eleven in number.

One of the most noticeable features of the underground system in London is that it connects these stations by
means of a continuous circuit, or "circle," as it is there called. The line connecting the terminal stations is
called the "inner circle." There is also an extension at one end of this elliptical shaped circle which also makes
a complete circuit, and which is called the "middle circle," and a very much larger circle reaching the northern
portions of the city, which is called the "outer circle." The eastern ends of these three circles run for a
considerable distance on the same track. In addition to this the road branches off in a number of directions,
reaching those parts of the city which were not before accommodated by the surface roads, or more
properly the elevated or depressed roads, as there are no grade crossings.

With regard to the accommodation afforded by this system: it is a convenience for the residents of the

western and southern parts of London, especially where they arrive in the city at any of the terminal stations
on the line of the "circle," as they can change to the underground. They can reach the eastern end of the
"circle," at which place is located the bank and the financial section of London, in a comparatively short time.
For example, passengers arriving at Charing Cross, Victoria or Paddington stations, can change to the
underground, and in ten, fifteen and thirty minutes respectively, reach the Mansion House or Cannon street
stations, which are the nearest to the Bank of England. In a similar manner those arriving at Euston, St.
Pancras or King's Cross on the northern side of the "circle," can reach Broad Street station in ten or fifteen
minutes, which station is nearest the bank on that side of the "circle."

In a number of cases the underground station is in the same building or directly connected by passages with
the terminal stations of the roads leading into the city. Examples of this kind would be such stations as
Cannon Street, Victoria or Paddington. They are not, however, sufficiently convenient to allow the
transference of baggage so as to accommodate through passengers desiring to make connection from one
station to another across the city. Hand baggage only is carried, about the same as it is on the elevated road
in New York. The method of cross town transfer, passengers and baggage, is invariably done by small
omnibuses, which all the railroads maintain on hand for that special purpose. A very large proportion of the
travel, however, if not the largest, is obtained by direct communication by means of the "circle" on branch
lines with the various residential portions of north, west and south London.

Approximately on the underground railroad the fare is one cent per mile for third class, one cent and a half
for second class, and two cents for first class, but no fare is less than a penny, or two cents. Omnibus fares in
some instances are as low as a penny for two miles. This is not by any means the rule, and is only to be found
on competing lines. The average fare would be a penny a mile or more.

The fares on the main lines which accommodate the suburban traffic are somewhat higher than on the
underground, perhaps 50 per cent. more. In every case, on omnibus, tram cars or railroads, the rates are
charged according to distance. The system such as in use on our electric, cable and horse cars and on the
elevated road in New York, of charging a fixed fare, is not in use anywhere.

The ticket offices of the underground roads are generally on a level with the street. In some instances both
the uptown and downtown trains are approached from one entrance, but generally there is an entrance at
either side of the railroad, similar to the elevated railroad system. In purchasing a ticket, the destination,
number of the class, and whether it is a single or return ticket have to be given. The passenger then descends
by generally well lighted stairways to the station below, and his ticket is punched by the man at the gate. He
then has to be careful about two things; first, to place himself on that part of the platform where the particular
class which he wishes to take stops, and secondly, to get on to the right train. In the formation of the train the
first class coaches are placed in the center, the second and third class respectively at the front and rear end.
There are signs which indicate where passengers are to wait, according to the class. There is a sign at the
front end of the engine, which to those initiated sufficiently indicates the destination of the train. The trains are
also called out, and at some stations there is an obscure indicator which also gives the desired information.
The stations are from imperfectly to well lighted, generally from daylight which sifts down from the smoky
London atmosphere through the openings above. The length of the train averages about eight carriages of
four compartments, each compartment holding ten persons, making a carrying capacity of 320 passengers.
The equipment of the cars is very inferior. The first class compartments are upholstered and cushioned in blue
cloth, the second class in a cheaper quality, while most of the third class compartments have absolutely
nothing in the way of a cushion or covering either on the seat or back, and are little better than cattle pens.
The width of the compartment is so narrow that the feet can easily be placed on the opposite seat, that is, a
very little greater distance than would be afforded by turning two of our seats face to face. The length of the
compartment, which is the width of the car, is about a foot and a half less than the width of our passenger
cars, about equal to our freight cars. Each compartment is so imperfectly lighted by a single lamp put into
position through the top of the car that it is almost impossible to read.

The length of time which a train remains at a station is from thirty to forty seconds, or from three to four times
the length of time employed at the New York elevated railroad stations. The reason for this is that a large
proportion of the doors are opened by passengers getting in or out, and all these have to be shut by the
station porter or guard of the train before the train can start. If the train is crowded one has to run up and
down to find a compartment with a vacant seat, and also hunt for his class, and as each class is divided into
smoking and non-smoking compartments, making practically six classes, it will be observed that all this takes
time, especially when you add the lost time at the ticket office and gate.

The ventilation of the tunnels and even the stations is oftentimes simply abominable, and although the roads
are heavily patronized there is a great amount of grumbling and disfavor on this account. The platforms of the
stations are flush with those of the cars, so that the delay of getting in or out is very small, but the doors are
so low that a person above the average height has to stoop to get in, and cannot much more than stand
upright with a tall hat on when he is once in the car. The monitor roof is unknown.

The trains move with fair speed and the stations are plainly and liberally marked, so that the passenger has
little difficulty in knowing when to get out. There are two signs in general use on English railroads which are
very simple and right to the point, namely, "Way Out" and "Way In," so that when a passenger arrives at a

station he has no question how to get out of it. The ticket is given up as the passenger leaves the station.
There is nothing to prevent a passenger with a third class ticket getting into a first class compartment
excepting the ominous warning of 40 shillings fine if he does so, and the liability of having his sweet dreams
interrupted by an occasional inspector who asks to see the denomination of his ticket. All compartments
intended for the use of smokers are plainly marked and are to be found in each class. Almost the entire part
of the railroads within the thickly settled portions of the city run in closed tunnels. Outside of this they
frequently run in open cuttings, and still further out they run on to elevated tracks.

With regard to the equipment of the suburban or surface lines not belonging to the underground system the
description is about the same. The cars are generally four compartments long and sometimes not exceeding
three. They are coupled together with a pair of links and fastened to the draw bar on one car and the other
thrown over a hook opposite and brought into tension by a right and left hand screw between the links. This
is obviously very inconvenient for shunting purposes, especially as the cars are not provided with hand
brakes and no chance to get at them if there were any. Consequently it appears that when a train is made up
it stays so for an indefinite period. A load of passengers is brought into the station and the train remains in
position until it is ready to go out. As the trains run very frequently this appears to be a very economical
arrangement, as no shunting tracks are needed for storage. The engine which brings the train in of course
cannot get out until the train goes out with the next load. Turn tables for the locomotives are but very little
used, as they run as double enders for suburban purposes.

In conclusion it will be safe to say that the problem of rapid transit for a city as large as London is far from
solved by the methods described. Although there are a great many miles of underground lines and main lines,
as they have been called throughout the paper, and although grade crossings have been entirely abolished,
allowing the trains to run at the greatest speed suitable to their frequency, still there are a great many sections
which have to depend entirely upon the omnibus or tram car. The enormous expense entailed by the
construction of the elevated structures can hardly be imagined. We have but one similar structure in this
country, which is that running from the Schuylkill River to Broad Street station, in Philadelphia. The
underground system is even more expensive, especially in view of the tremendous outlay for damages. This
goes to show that money has not been spared to obtain rapid transit.

After all, the means to be depended upon when one desires to make a rapid trip from one part of the city to
another is the really admirable, cheap, always ready, convenient and comfortable London hansom; while the
way to see London is from the top of an omnibus, the most enjoyable, if not the most expeditious, means of
conveyance.

[1]

Abstract from a paper read before the Boston Society of Engineers, in April, 1890.

[Continued from SUPPLEMENT, NO. 809, page 12930.]

RIVETED JOINTS IN BOILER SHELLS.1

By WILLIAM BARNET LE VAN.

FIG. 11.

Fig. 11 represents the spacing of rivets composed of steel plates three-eighths inch thick, averaging 58,000

pounds tensile strength on boiler fifty-four inches diameter, secured by iron rivets seven-eighths inch
diameter. Joints of these dimensions have been in constant use for the last fourteen years, carrying 100
pounds per square inch.

Punching Rivet Holes.—Of all tools that take part in the construction of boilers none are more important, or
have more to do, than the machine for punching rivet holes.

That punching, or the forcible detrusion of a circular piece of metal to form a rivet hole, has a more or less
injurious effect upon the metal plates surrounding the hole, is a fact well known and admitted by every
engineer, and it has often been said that the rivet holes ought all to be drilled. But, unfortunately, at present
writing, no drilling appliances have yet been placed on the market that can at all compare with punching
apparatus in rapidity and cheapness of working. A first-class punching machine will make from forty to fifty
holes per minute in a thick steel plate. Where is the drilling machine that will approach that with a single drill?

The most important matter in punching plates is the diameter of the opening in the bolster or die relatively to
that of the punch. This difference exercises an important influence in respect not only of easy punching but
also in its effect upon the plate punched. If we attempt to punch a perfectly cylindrical hole, the opening in the
die block must be of the same diameter as the point of the punch, or, at least, a very close fit. The point of
the punch ought to be slightly larger in diameter than the neck, or upper part, as shown in Figs. 12 and 13, so
as to clear itself easily. When the hole in the bolster or die block is of a larger diameter than the punch, the
piece of metal thrust out is of larger diameter on the bottom side, and it comes out with an ease proportionate
to the difference between the lower and upper diameters; or, in other words, it produces a taper hole in the
plate, but allows the punching to be done with less consumption of power and, it is said, with less strain on
the plate.

FIG. 12. and FIG. 13.

As to the difference which should exist between the diameter of the punch and the die hole, this varies a little
with the thickness of the plate punched, or should do so in all carefully executed work, for it is easy to
understand that the die which might give a suitable taper in a three-fourths inch plate would give too great a
taper in a three-eighths inch plate. There is no fixed rule; practical experience determines this in a rough and
ready way—often a very rough way, indeed, for if a machine has to punch different thicknesses of plate for
the same size of rivets, the workman will seldom take the trouble to change the die with every variation of
thickness. The maker of punches and dies generally allows about three sixty-fourths or 0.0468 of an inch
clearance.

The following formula is also used by punch and die makers:

Clearance = D = d + 0.2t

where

D = diameter of hole in die block;
d = diameter of cutting edge of punch;
t = thickness of plate in fractions of an inch;

that is to say, the diameter of the die hole equals diameter of punch plus two-tenths the thickness of the plate
to be punched.

Example.—Given a plate 3/8 or 0.375 of an inch thick, the diameter of the punch being 13/16 or 0.8125 of
an inch, then the diameter of the die hole will be as follows:

Diameter of die hole = 0.8125 + 0.375 X 0.2 = 0.8875 inch diameter,
or say 7/8 or 0.875 inch diameter.

Punches are generally made flat on their cutting edge, as shown in Fig. 12. There are also punches made
spiral on their cutting edge, as shown in Fig. 13. This punch, instead of being flat, as in Fig. 12, is of a helical
form, as shown in Fig. 13, so as to have a gradual shearing action commencing at the center and traveling
round to the circumference. Its form may be explained by imagining the upper cutter of a shearing machine
being rolled upon itself so as to form a cylinder of which its long edge is the axis. The die being quite flat, it
follows that the shearing action proceeds from the center to the circumference, just as in a shearing machine it
travels from the deeper to the shallower end of the upper cutter. The latter is not recommended for use in
metal of a thickness greater than the diameter of the punch, and is best adapted for thicknesses of metal two-
thirds the diameter of the punch.

Fig. 14 shows positions of punch and attachments in the machine.

FIG. 14.

It is of the greatest importance that the punch should be kept sharp and the die in good order. If the punch is
allowed to become dull, it will produce a fin on the edge of the rivet hole, which, if not removed, will cut into
the rivet head and destroy the fillet by cutting into the head. When the punch is in good condition it will leave
a sharp edge, which, if not removed, will also destroy the fillet under the head by cutting it away.

Punching possesses so many advantages over drilling as to render it extremely important that the operation
should be reduced to a system so as to be as harmless as possible to the plate. In fact, no plate should be
used in the construction of a boiler that does not improve with punching, and further on I will show by the
experiments made by Hoopes & Townsend, of Philadelphia, that good material is improved by punching;
that is to say, with properly made punches and dies, by the upsetting around the punched hole, the value of
the plate is increased instead of diminished, the flow of particles from the hole into the surrounding parts
causing stiffening and strengthening.

Drilling Rivet Holes.—In the foregoing I have not referred to the drilling of rivet holes in place of punching.
The great objection to drilling rivet holes is the expense, from the fact that it takes more time, and when
drilled of full rivet size we are met with the difficulty of getting the rivet holes to correspond, as they are when
punched of full rivet diameter. When two plates are drilled in place together, the drill will produce a burr
between the two plates—on account of their uneven surfaces—which prevents them being brought together,
so as to be water and steam tight, unless the plates are afterward separated and the burr removed, which, of
course, adds greatly to the expense.

The difference in strength between boiler plates punched or drilled of full rivet size may be either greater or
less than the difference in strength between unperforated plates of equal areas of fracture section. When the
metal plates are very soft and ductile, the operation of punching does no appreciable injury. Prof. Thurston
says he has sometimes found it actually productive of increased strength; the flow of particles from the rivet
hole into the surrounding parts causing stiffening and strengthening. With most steel and hard iron plates the
effect of punching is often to produce serious weakening and a tendency to crack, which in some cases has
resulted seriously. With first class steel or iron plates, punching is perfectly allowable, and the cost is twenty-
five per cent. less than drilling; in fact, none but first class metal plates should be used in the construction of
steam boilers.

In the original punching machines the die was made much larger than the punch, and the result was a conical

taper hole to receive the rivet. With the advanced state of the arts the punch and die are accurately fitted; that
is to say, the ordinary clearance for a rivet of (say) three-fourths of an inch diameter, the dies have about
three sixty-fourths of an inch, the punch being made of full rivet size, and the clearance allowed in the
diameter of the die.

Take, for example, cold punched nuts. Those made by Messrs. Hoopes & Townsend, Philadelphia, when
taken as specimens of "commercial," as distinguished from merely experimental punching, are of considerable
interest in this connection, owing to the entire absence of the conical holes above mentioned.

When the holes are punched by machines properly built, with the punch accurately fitted to the die, the effect
is that the metal is made to flow around the punch, and thus is made more dense and stronger. That some
such action takes place seems probable, from the appearance of the holes in the Hoopes & Townsend nuts,
which are straight and almost as smooth as though they were drilled.

Therefore I repeat that iron or steel that is not improved by proper punching machinery is not of fit quality to
enter into the construction of steam boilers.

STRENGTH OF PUNCHED AND DRILLED IRON BARS.

HOOPES & TOWNSEND.

Thickness of bar

in inches.

Thickness outside of hole

in inches.

Punched bars

broke in pounds.

Drilled bars

broke in pounds.

3/8 or
0.375
3/8 or
0.375
31,740
28,000

3/8 or
0.375
3/8 or
0.375
31,380
26,950

5/8 or
0.625
1/4 or
0.25
18,820
18,000

5/8 or
0.625
1/4 or
0.25
18,750
17,590

5/8 or
0.625
3/16 or
0.1875
14,590
13,230

5/8 or
0.625
3/16 or
0.1875
15,420
13,750

5/8 or
0.625
1/8 or
0.125
10,670
9,320

5/8 or
0.625
1/8 or
0.125
11,730
9,580

It will be seen from the above that the punched bars had the greatest strength, indicating that punching had
the effect of strengthening instead of weakening the metal. These experiments have given results just the
reverse of similar experiments made on boiler plates; but the material, such as above experimented upon, is
what should be placed in boilers, tough and ductile, and the manner of, and care taken in, punching
contribute to these results.

It is usual to have the rivet holes one-sixteenth of an inch in diameter larger than the rivets, in order to allow
for their expansion when hot; it is evident, however, that the difference between the diameters of the rivet
hole and of the rivet should vary with the size of the rivet.

The hole in the die is made larger than the punch; for ordinary work the proportion of their respective
diameters varies from 1:1.5 to 1:2.

As I have before stated, the best plate joint is that in which the strength of the plate and the resistance of the
rivet to shearing are equal to each other.

In boilers as commercially made and sold the difference in quality of the plates and rivets, together with the
great uncertainty as to the exact effect of punching the plates, have, so far, prevented anything like the
determination either by calculation or experiment of what might be accepted as the best proportions of
riveted joints.

In regard to steel plates for boilers Mr. F.W. Webb, of Crewe, England, chief engineer of the London and
Northwestern Railway, has made over 10,000 tests of steel plates, but had only two plates fail in actual
work; these failures he thought were attributable solely to the want of care on the part of the men who
worked the plates up.

All their rivet holes for boilers were punched in a Jacquard machine, the plates then annealed, and afterward
bent in rolls; they only used the reamer slightly when they had three thicknesses of plate to deal with, as in
butt joints with inside and outside covering strips. These works turn out two locomotive boilers every three
days.

The Baldwin Locomotive Works, which turn out on an average three locomotives per day, punch all their
rivet holes one sixteenth inch less in diameter and ream them to driven rivet size when in place. They also use
rivets with a fillet formed under head made in solid dies.

Rivets.—Rivets of steel or iron should be made in solid dies. Rivets made in open dies are liable to have a fin
on the shank, which prevents a close fit into the holes of the plates. The use of solid dies in forming the rivet
insures a round shank, and an accurate fit in a round hole. In addition, there is secured by the use of solid
dies, a strong, clean fillet under the head, the point where strength is most needed.

Commencing with a countersunk head as the strongest form of head, the greater the fillet permissible under
the head of a rivet, or bolt, the greater the strength and the decrease in liability to fracture, as a fillet is the life
of the rivet.

If rivets are made of iron, the material should be strong, tough, and ductile, of a tensile strength not exceeding
54,000 pounds per square inch, and giving an elongation in eight inches of not less than twenty-five per
cent. The rivet iron should be as ductile as the best boiler plate when cold. Iron rivets should be annealed and
the iron in the bar should be sufficiently ductile to be bent cold to a right angle without fracture. When heated
it should be capable of being flattened out to one-third its diameter without crack or flaw.

FIG. 15. Solid Die Rivet. and FIG. 16. Open Die Rivet.

If rivets are made of steel they must be low in carbon, otherwise they will harden by chilling when the hot
rivets are placed in the cold plates. Therefore, the steel must be particularly a low grade or mild steel. The
material should show a tensile strength not greater than 54,000 pounds per square inch and an elongation in
eight inches of thirty per cent. The United States government requirements are that steel rivets shall flatten
out cold under the hammer to the thickness of one-half their diameter without showing cracks or flaws; shall
flatten out hot to one-third their diameter, and be capable of being bent cold in the form of a hook with
parallel sides without cracks or flaws. These requirements were thought at first to be severe, but the makers
of steel now find no practical difficulty in meeting these specifications.

The forming of the head of rivets, whether of steel or iron, and whether the heads are conical or semi-
spherical, should not be changed by the process of riveting. The form of the head is intended to be
permanent, and this permanent form can only be retained by the use of a "hold fast," which conforms to the
shape of the head. In the use of the flat hold fast (in general use in a majority of boiler shops) the form of the
head is changed, and if the rivet, by inadequate heating, requires severe hammering, there is danger that the
head of the rivet may be "punched" off. By the use of a hold fast made to the shape of the rivet head, this
danger is avoided and the original form of the head is retained. This feature of the use of proper rivet tools in
boiler shops has not received the attention it deserves. Practical use of the above named hold fast would
soon convince the consumers of rivets of its value and efficiency.

The practice of driving rivets into a punched rivet hole from which the fin or cold drag, caused by the
movement of the punch, has not been removed by reaming with a countersunk reamer, or better still a
countersunk set, should be condemned, as by driving the hot rivet head down against the fin around the hole
in the cold plate caused by the action of punching the countersunk fillet is not only destroyed, but it is liable to
be driven into the head of the rivet, partially cutting the head from the shank. If the rivet is driven into a hole
that has been punched with a sharp punch and sharp die, the result is that the fillet is cut off under the head,
and the riveted end is also cut, and does not give the clinch or hold desired. That is to say, rivet holes in
plates to be riveted should have the burr or sharp edge taken off, either by countersinking, by reamer, or set.

Heating of Rivets.—Iron rivets are generally heated in an ordinary blacksmith's or rivet fire having a forced
blast; they are inserted with the points down into the fire, so that the heads are kept practically cool.

Steel rivets should be heated in the hearth of a reverberatory furnace so arranged that the flame shall play

over the top of the rivets, and should be heated uniformly throughout the entire length of the rivet to a cherry
red. Particular attention must be given to the thickness of the fire in which they are heated.

Steel, of whatever kind, should never be heated in a thin fire, especially in one having a forced blast, such as
an ordinary blacksmith's or iron rivet furnace fire. The reason for this is that more air passes through the fire
than is needed for combustion, and in consequence there is a considerable quantity of free oxygen in the fire
which will oxidize the steel, or in other words, burn it. If free oxygen is excluded steel cannot burn; if the
temperature is high enough it can be melted and will run down through the fire, but burning is impossible in a
thick fire with a moderate draught.

This is an important matter in using steel rivets and should not be overlooked; the same principle applies to
the heating of steel plates for flanging.

Riveting.—There are four descriptions of riveting, namely:

(1) Hammered or hand riveting.
(2) Snapped or set.
(3) Countersunk..
(4) Machine.

For good, sound work, machine riveting is the best.

Snapped riveting is next in quality to machine riveting.

Countersunk riveting is generally tighter than snapped, because countersinking the hole is really facing it; and
the countersunk rivet is, in point of fact, made on a face joint. But countersinking the hole also weakens the
plate, inasmuch as it takes away a portion of the metal, and should only be resorted to where necessary, such
as around the front of furnaces, steam chests or an odd hole here and there to clear a flange, or something of
that sort.

Hammered riveting is much more expensive than machine or snapped riveting, and has a tendency to
crystallize the iron in the rivets, causing brittleness.

In the present state of the arts all the best machine riveters do their work by pressure, and not by impact or
blow.

The best machines are those of the hydraulic riveting system, which combines all of the advantages and
avoids all the difficulties which have characterized previous machine systems; that is to say, the machine
compresses without a blow, and with a uniform pressure at will; each rivet is driven with a single progressive
movement, controlled at will. The pressure upon the rivet after it is driven is maintained, or the die is retracted
at will.

FIG. 17.

Hydraulic riveting has demonstrated not only that the work could be as well done without a blow, but that it
could be better done without a blow, and that the riveted material was stronger when so secured than when
subjected to the more severe treatment under impact.

What is manifestly required in perfect riveting is that the metal of the rivet while hot and plastic shall be made
to flow into all the irregularities of the rivet holes in the boiler sheets; that the surplus metal be formed into
heads as large as need be, and that the pressure used to produce these results should not be in excess of
what the metal forming the boiler shall be capable of resisting.

It is well known that metals, when subjected, either cold or hot, to sufficient pressure, will obey almost
exactly the same laws as fluids under similar conditions, and will flow into and fill all the crevices of the

chamber or cavity in which they are contained. If, therefore, a hot rivet is inserted into the holes made in a
boiler to receive it, and is then subjected to a sufficient pressure, it will fill every irregularity of the holes, and
thus fulfill one of the conditions of perfect riveting. This result it is impossible to accomplish with perfection or
certainty by ordinary hand riveting, in doing which the intermittent blows of an ordinary hammer are used to
force the metal into the holes. With a hydraulic riveting machine, however, an absolutely uniform and
continuous pressure can be imparted to each rivet, so as to force the hot metal of the rivet into all the
irregularities of the holes in the same way as a hydraulic ram will cause water to fill any cavity, however
irregular.

FIG. 18.

In order to illustrate the relative advantages of machine over hand riveting, two plates were riveted together,
the holes of which were purposely made so as not to match perfectly. These plates were then planed through
the center of the rivets, so as to expose a section of both the plates and rivets. From this an impression was
taken with printer's ink on paper and then transferred to a wooden block, from which Figs. 17 and 18 were
made.

The machine-driven rivet is marked a, and b represents the hammered rivet.

It will be observed that the machine rivet fills the hole completely, while the hand rivet is very imperfect. This
experiment was tried several times, with similar results each time.

The hand rivet, it will be observed, filled up the hole very well immediately under the head formed by the
hammer; but sufficient pressure could not be given to the metal—or at least it could not be transferred far
enough—to affect the metal at some distance from the driven head. So great is this difficulty that in hand
riveting much shorter rivets must be used, because it is impossible to work effectively so large a mass of
metal with hammers as with a machine. The heads of the machine rivets are, therefore, larger and stronger,
and will hold the plates together more firmly than the smaller hammered heads.

To drive rivets by hand, two strikers and one helper are needed in the gang, besides the boy who heats and
passes the rivets; to drive each five-eighths inch rivet, an average of 250 blows of the hammer is needed, and
the work is but imperfectly done. With a machine, two men handle the boiler, and one man works the
machine; thus, with the same number of men as is required in riveting by hand, five rivets are driven each
minute.

The superior quality of the work done by the machine would alone make its use advantageous; but to this is
added greatly increased amount of work done.

The difference in favor of the riveting machine over hand riveting is at least ten to one.

In a large establishment a record of the number of rivets driven by the hand-driving gang, also by the gang at
the steam-riveting machine for a long period of time, in both cases making no allowances of any kind of
delays, the rivets driven per month by each was—for the hand driven rivets at the rate of twelve rivets per
hour, and for the machine driven rivets, 120 per hour. In the case of the hand driven rivets the boiler remains
stationary and the men move about it, while the machine driven rivets require the whole boiler to be hoisted
and moved about at the riveting machine to bring each hole to the position required for the dies.
Notwithstanding the trouble involved in handling and moving the boiler, it shows that it is possible to do ten
times as much work, and with less skilled labor, by the employment of the riveting machine.

Calking.—One great source of danger in boiler making is excessive joint calking—both inside and out—
where a sharp nosed tool is employed, and for the reason that it must be used so close to the inner edge of
plate as to indent, and in many cases actually cut through the skin of the lower plate. This style of calking puts
a positive strain upon the rivets, commencing distortion and putting excessive stress upon rivets—already in
high tension before the boiler is put in actual use. It is, I hope, rapidly becoming a thing of the past.

With a proper proportion of diameter and pitch of rivet, all that is required is the use of a light "fuller tool" or
the round-nosed tool used in what is known to the trade as the "Connery system."

There is but little need of calking if means are taken to secure a clean metal-to-metal face at the joint
surfaces. When the plates are put together in ordinary course of manufacture, a portion of the mill scale is left
on, and this is reduced to powder or shaken loose in the course of riveting and left between the plates, thus
offering a tempting opening for the steam to work through, and is really cause of the heavy calking that puts
so unnecessary a pressure on both plate and rivet. A clean metallic joint can be secured by passing over the
two surfaces a sponge wet with a weak solution of sal-ammoniac and hot water, an operation certainly cheap
enough both as to materials and labor required.

FIG. 19.

The above cut, Fig. 19, gives an illustration of calking done by sharp-nosed and round nosed tools,
respectively. It will be seen by Fig. 20 that the effect of a round-nosed tool is to divide the plate calked, and
as the part divided is well driven toward the rivets, a bearing is formed at a, from one-half to three-fourths of
an inch, which increases the strength of joint, and will in no way cut or injure the surface of the under plate. A
perfect joint is thus secured.

FIG. 20.

[1]

A paper read at a meeting of the Franklin Institute. From the journal of the Institute.

THE NEW BRITISH BATTLE SHIP EMPRESS OF INDIA.

The launching of this first-class battle ship was successfully carried out at Pembroke Dockyard on May 7.
She is the second of a class of eight battle ships built and building under the Naval Defense Act of 1889,
which were specially designed to take part in general fleet actions in European waters. The leading
dimensions are: Length, between perpendiculars, 380 ft.; breadth, extreme, 75 ft.; mean draught of water, 27
ft. 6 in.; and displacement at this draught, 14,150 tons, which surpasses that of any other ship in the navies of
the world. Previous to the launching of the Royal Sovereign—a sister vessel—which took place at
Portsmouth in February last, the largest war ships in the British navy were the Nile and Trafalgar, each of
12,500 tons, and these were largely exceeded in displacement by the Italia, of 13,900 tons, and the Lepanto,

of 13,550 tons, belonging to the Italian navy.

The Empress of India is built throughout of mild steel, the stem and stern post, together with the shaft
brackets, being of cast steel. Steel faced armor, having a maximum thickness of 18 in., extends along the
sides for 250 ft. amidships, the lower edge of the belt being 5 ft. 6 in. below the normal water line. The belt is
terminated at the fore and after ends by transverse armored bulkheads, over which is built a 3 in. protective
steel deck extending to the ends of the vessel and terminating forward at the point of the ram. Above the belt
the broadside is protected by 5 in. armor, the central battery being inclosed by screen bulkheads of the same
thickness. The barbettes, which are formed of armor 17 in. thick, rise from the protective deck at the fore
and after ends of the main belt. The principal armor throughout is backed by teak, varying in thickness from
18 in. to 20 in., behind which is an inner skin of steel 2 in. thick. The engines are being constructed by
Messrs. Humphreys, Tennant & Co, London, and are of the vertical triple expansion type, capable of
developing a maximum horse power of 13,000 with forced draught and 9,000 horse power under natural
draught, the estimated speeds being 16 and 17½ knots respectively at the normal displacement. The regular
coal supply is 900 tons, which will enable the ship to cover a distance of 5,000 knots at a reduced speed of
ten knots and about 1,600 knots at her maximum speed. The main armament of the Empress will consist of
four 67 ton breechloading guns mounted in pairs en barbette. The secondary armament includes ten 6 in.
100 pounder quick firing guns, four being mounted on the main deck and six in the sponsons on the upper
deck, sixteen 6 pounder and nine 3 pounder quick-firing guns, in addition to a large number of machine guns.

The largest guns at present mounted in any British warship are the 110 ton guns mounted in the Benbow
class, and the difference between these weapons and those to be carried by the Empress of India is very
marked.

The projectile fired from either of the Benbow's heavy gun weighs 1,800 lb., and is capable of penetrating 35
in. of unbacked wrought iron at a distance of 1,000 yards. The projectile fired from the 67 ton guns of the
Empress of India will have much less penetrating power, being only equal to 27 in. of wrought iron with a full
charge of 520 lb. of prismatic brown powder, the missile weighing 1,250 lb. or about one-half less than the
weight of the shot used with the 110 ton gun. It will thus be seen that the ordnance of the Benbow can
penetrate armor that would defy the attack of the guns of the Empress. It should be said, however, that the
heavy artillery of the latter vessel is capable of penetrating any armor at present afloat, and is carried at a
much greater height above the designed load water line than in any existing battle ship, either in the British or
foreign navies. The armor being of less weight, too, enables the new ship, and others of her class, to carry an
auxiliary armament of unprecedented weight and power.

The Empress will be lighted throughout by electricity, the installation comprising some 600 lights, and will be
provided with four 25,000 candle power search lights, each of which will be worked by a separate dynamo.
The ship has been built from the designs of Mr. W.H. White, C.B., Director of Naval Construction, and will
be fitted out for the use of an admiral, and when commissioned her complement of officers and men will
number 700.—Industries.

THE "IRON GATES" OF THE DANUBE.

The work of blowing up the masses of rock which form the dangerous rapids known as the Iron Gates, on
the Danube, was inaugurated on September 15, 1890, when the Greben Rock was partially blown up by a
blast of sixty kilogrammes of dynamite, in the presence of Count Szapary, the Hungarian premier; M. Baross,
Hungarian minister of commerce; Count Bacquehem, Austrian minister of commerce; M. Gruitch, the Servian
premier; M. Jossimovich, Servian minister of public works; M. De Szogyenyi, chief secretary in the Austro-
Hungarian ministry of foreign affairs; and other Hungarian and Servian authorities. Large numbers of the
inhabitants had collected on both banks of the Danube to witness the ceremony, and the first explosion was
greeted with enthusiastic cheers. The history of this great scheme was told at the time the Hungarian
Parliament passed the bill on the subject two years ago. It is known that the Roman Emperor Trajan,
seventeen centuries ago, commenced works, of which traces are still to be seen, for the construction of a
navigable canal to avoid the Iron Gates.

For the remedy of the obstruction in the Danube, much discussed of late years, there were two rival systems
—the French, which proposed to make locks, and the English and American, which was practically the same
as that...